Generating a hard disk drive (HDD) data track repeatable runout (RRO) compensation value for a target track involves querying at least one RRO table for a closest track to the target track external servo target (EST) and identifying an EST.sub.x corresponding to the closest track, computing a first absolute value of the difference between the EST and the EST.sub.x, and responsive to the first absolute value being less than an approximation threshold, setting the RRO compensation value for the target track to the RRO compensation value for the closest track. Else, querying the RRO table(s) for each adjacent track to the target track, computing the difference between the ESTs for the adjacent tracks, and responsive to the second absolute value being less than an interpolation threshold, determining an RRO compensation value for the target track based on RRO compensation values corresponding to the adjacent tracks.

The technology disclosed herein pertains to a system and method for managing off-track retry. An implementation of a method of determining offset direction for read off-track retry includes storing analog to digital converter (ADC) values of data read from a data sector by a data reader in a read channel buffer, calculating an indicator value of the distribution of the ADC values, determining an amount of offset for the data reader based on the indicator value, and moving the data reader by the amount of offset before performing a read retry operation.

According to one embodiment, a magnetic disk device including a magnetic disk, measures an error rate of the magnetic disk, sets an area to be affected by sputtering claws generated during manufacturing of the magnetic disk based on the measured error rate, and writes reference data used for measuring the error rate to the set area. Then, the magnetic disk device manages the data written to the magnetic disk based on the error rate when reading the reference data written to the set area.

There are provided a memory system and an operating method thereof. A memory system includes: a plurality of storage regions, each including a plurality of memory cells; and a controller configured to provide a plurality of read retry sets, determine an applying order of the plurality of read retry sets based on characteristics of a read error occurred in a first storage region among the plurality of storage regions, and apply at least one of the read retry sets, based on the applying order, for a read retry operation performed on the first storage region.

A memory system may include: a memory device including a plurality of storage regions; and a controller. The controller may be coupled between a host and the memory device, and perform a read retry operation when a read error occurs in any one of the storage regions based on occurrence possibilities for a plurality of different type of defects in any one storage region where a read error occurred.

A method includes detecting a read error during a first read operation by a read sensor on a first track on a data storage medium. The method also includes, after the read error is detected, performing a second read operation by the read sensor on the first track, carrying out bit error value (BEV) measurements for the second read operation, and determining, from the BEV measurements, whether the read sensor produces a marginal BEV, which is between first and second predetermined BEV thresholds. In response to determining that the read sensor produces the marginal BEV, a third read operation by the read sensor on the first track is carried out, and BEV measurements for the third read operation are performed. When the BEV measurements from the second and third read operations meet at least one predetermined read sensor instability criterion, it is concluded that the read sensor is unstable.

A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, wherein each data track comprises a plurality of data segments. First data is written to data segments of a first data track, and second data is written to data segments of a second data track. After writing the second data, the first data is read at multiple off-track offsets of the first data track to measure an average off-track read capability (OTRC) of the first data track. A cross-track profile is generated for a first data segment of the first data track, and at least part of the cross-track profile is correlated with the measured average OTRC.

The technology disclosed herein provides a method for generating an on-cylinder limit (OCLIM), the method including performing servo certification of a plurality of drives in a storage device to generate servo adaptive parameters (SAPs) by heads, generating a plurality of read adjust parameters (RAPs) by heads for the plurality of drives, generating an interim OCLIM value based on the SAPs by heads and RAPs by zones, and operating a disc drive write element using the interim OCLIM value.

According to one embodiment, a magnetic disk device includes a disk including a first region and a second region different from the first region, a head that writes data on the disk and reads data from the disk, an actuator that positions the head on the disk, and a controller which positions the head by driving the actuator and writes data in the first region and the second region with the head, a skew angle of the head with respect to a circumferential direction of the disk varying within a first angle in the first region, and varying, in the second region, from a second angle larger than the first angle to a third angle larger than the first angle and the second angle.

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of data tracks, including a first data track and a second data track. In connection with writing to at least part of the first data track, a quality metric is measured for at least part of the first data track. In connection with writing to at least part of the second data track, a refresh metric is updated based on the write to at least part of second data track and the quality metric measured for the first data track, and at least the first data track is refreshed based on the refresh metric.